Method of uniting members



Aug. 15, 1933. w DIKE 1,922,668

METHOD OF UNITING MEMBERS Filed March 1, 1932 INVENTOR Patented Aug. 15, 1933 METHOD OF UNITING MEMBERS Theodore Williams Dike, New Westminster,

British Columbia, Canada, assignor, by mesne assignments, to Laminating Patents Corporation, Seattle, Wash, a Corporation of Delaware Application March 1, 1932. Serial No. 596,070

17 Claims.

This invention relates to a method of uniting objects adhesively and more specifically to methods .of forming plywood which involve the use of a powdered adhesive.

This application is a continuation in part of the following copending applications of Theodore Williams Dike, Serial No. 455,977, filed May 26, 1930, Patent No. 1,851,950, issued March 29, 1932, Serial No. 455,978, filed May 26, 1930, Patent No. 1,851,951, issued March 29, 1932, and

Serial No. 456,814, filed May 28, 1930, Patent No. 1,851,952, issued March 29, 1932.

In general it is an object of the invention to provide a method of the character described which will efficiently attain the desired results, which is simple and economical to perform, and which can be expeditiously, conveniently and safely carried out.

Another object of the invention is to provide a particularly uniform bond between the members united.

Another object is to provide an improved method for applying a liquid to powdered adhesive in situ.

Another object is to provide a method for uniformly applying a plasticizing or other liquid agent to the particles of an adhesive in powder form.

Another object is to provide a method for apsuch that the physical and chemical forces set up tend to retain substantially all of said liquid in contact with said adhesive.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the sev eral steps and the relation and order of one or more of such steps with respect to each of the others thereof, which will be exemplified in the process hereinafter disclosed, and the scope of the application of which will be indicated in the claims. 7,

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:

Figure 1 is a schematic cross-sectional view showing an operation involved in a method embodying the invention;

Fig. 2 is a schematic cross-sectional view showing an operation not contemplated by the invention, but illustrated by way of contrast with the operation shown in Fig. 1;

Fig. 3 is a diagrammatic side view exempliplying a liquid to a powdered adhesive in situfying one method whereby plywood may be formed in accordance with the invention; and

Fig. 4 is a diagrammatic side view exemplifying another method whereby plywood may be formed in accordance with the invention.

In bonding procedures, such, for example, as the formation of plywood, a large number of advantages attend the use of an adhesive-providing material which is in discrete-particle form, particularly in powder form, when applied to a surface to be incorporated. In many instances it is desirable to provide also a liquid as a plasticizing medium or otherwise, often in limited amounts. In many cases it is of importance that the liquid be applied upon the layer of particles on the surface Such a procedure assists in bringing the liquid into intimate contact with the adhesive particles and in preventing displacement of the particles.

Various difficulties attend the application of the liquid in relatively large drops, however, since the drops tend to wet the adhesive unevenly, to dissipate themselves to a considerable extent into the body of wood or other porous material of which one or another of the members may-be composed, to wet the adhesive unevenly, to cause blisters, to cause weak spots in the bond, and other drawbacks.

In the joining of bodies together, and especially in uniting laminations as in the formation of plywood, it is of great importance that the forces of cohesion be uniformly acting over the entire surface, and tendencies toward discolorations, blisters and weak portions in the bond are to be avoided.

With a view to obtaining these and other ends the present invention contemplates the application of the liquid in atomized form rather than in large drops. This is of advantage particularly in the application of a liquid after the ap-- plication of the powder, and also, in some instances, in the application of liquid to a surface prior-to the application of the adhesive particles, particularly when the presence of an excessive amount of water is to be avoided. It is of particular importance in procedures when only a limited amount of liquid is to be applied and wherein the liquid is projected toward the surface of wood or other porous material.

The application of a liquid such as water atomized sufficiently so that the particles have a diameter of not more than 0.006 inches has been foundparticularly effective in many instances.

Desirably the liquid as supplied is atomized sufficiently so that the particles thereof will substantially not exceed the size of the particles of the adhesive.

When a liquid in the form of large drops is sprayed onto a layer of powdered adhesive on the surface of a porous member such as wood, there is a marked tendency for the adhesive particles to be dislodged from their original position and also for the drops of liquid to penetrate immediately through the layer of adhesive particles and to dissipate itself to a considerable extent into the wood. The few particles of adhesive that are entrapped by each drop take up an excess of liquid. Between these is an excess of adhesive particles which have a limited amount of liquid. These suffer from deficiency of liquid, and the areas covered by the drops suffer from an excess of liquid, so

1 will be visible to the izers, Diesel injection nozzles,

; same 40 that an undesirable unevenness occurs. when, on the other hand, the liquid is applied in a finely-divided condition, for example within the limit above indicated, it tends to spread itself evenly over the particles and to moisten the same to a substantially similar extent.

In connection with these effects it may be noted that the weight of liquid in a given drop varies as the cube of radius, whereas the projected area varies only as the square thereof.

Desirably the liquid applied is of sufficient fineness so that no pronounced pattern of liquid naked eye. Any well known or suitable type of atomizing means may beutilized as may be desired in any particular case. Reference may be made to air pressure spray guns, spatter-plate atometc.. adapted to properly atomize the liquid.

when an atomized liquid is applied to a layer of particles of powdered adhesive material, the tends to commingle freely and evenly with the particles of the layer. as contrasted with the uneven effect when large drops of water are applied. The action may be likened to the action of mist on a dusty road.

It will accordingly be seen that the application of an equal amount of liquid is markedly more effective when applied in atomized condition than when applied in large drops, as well as giving markedly more uniform eifects. The liquid, moveover, tends to permeate the layer of powder substantially immediately.

This distinction is brought out in Figs. 1 and 2, wherein Fig. 1 shows a layer of adhesive particles 10 which are being wet by a liquid applied in atomized condition, as indicated at 11, and Fig. 2 shows by contrast a layer of adhesive particles 12, to which undesirably large drops of water are being applied, as by spraying.

It is of importance in effectively carrying out the invention that the powder and the liquid be applied with substantial uniformity over the surface to be incorporated.

By way 'of example there are illustrated in Figs. 3 and 4 two procedures for the formation of plywood wherein the invention may be utilized.

In Fig. 3, plies 14 of pre-cut veneer are disposed successively on a conveyor 15 and moved under a mechanism 16 whereby an adhesive is applied to the upper surface thereof in powdered form. This mechanism is diagrammatically illustrated as of the type disclosed and claimed in the copending application of Louis G. Merritt and Ericsson H. Merritt, Serial No. 452,257, filed June 5, 1931. Thereafter the plies are passed under a spraying mechanism 17, which rial, applyin t0 may be of the type disclosed and claimed in the copending application of Ericsson H. Merritt and Richard W. Stanley, Serial No. 535,822, filed May 8, 1931. This carries suitable atomizing means as indicated diagrammatically at 18. After the powder and liquid have been applied one ply 14 may be disposed upon another, and a third ply l9 superposed thereon to form a threeply product, and the assembly subjected to bonding conditions, for instance, pressure, or heat and pressure, as in a plywood press, such as indicated diagrammatically at 20. Alternately a ply 19 may be superposed on each ply 14 to form two-ply assemblies which may be pressed, or which may be again run under a mechanism 16 and 1'1 for example, and a further ply superposed before pressing, or assemblies of any suitable number of plies may be formed in any desired manner.

The procedure illustrated in Fig. 4 is similar and parts are similarly numbered. In this instance, however, a liquid is applied to the surface of the plies 14, as by a spraying mechanism 21 equipped with atomizer means 22 prior to the application of the powdered adhesive.

Any of a wide number of well known and suitable materials may be utilized to provide the adhesive, and water or any of a variety of pure or mixed liquids or liquid solutions may be utilized as a plasticizing medium or otherwise, as adapted to the requirements of a particular case.

Since certain changes may be made in carrying out the above process without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention, which, as a matter of language, mightbe said to fall therebetween.

Having described my invention, what I claim as new and desire to be secured by Letters Patent is:

1. A method of causing adhesion, comprising applying particles of adhesive-providing mate said particles 2. liquid in atomized condition, assembling and subjecting to bonding conditions.

2. A method of causing adhesion, comprising applying particles of adhesive-providing material, applying to said particles 9. liquid plasticizing medium in atomized condition, assembling and subjecting to bonding conditions.

3. A method of causing adhesion, comprising substantially uniformly applying substantially dry particles of adhesive-providing material, substantially uniformly applying to said particles a liquid in atomized condition, assembling and subjecting to bonding conditions.

4. A method of causing adhesion, comprising 4 said layer of particles substantially immediately, and subjecting to pressure with or without heat.

6. A method of causing adhesion, comprising applying a substantially even layer of substantially dry particles of adhesive-providing material, substantially uniformly applying to said layer a liquid sufliciently atomized to substantially uniformly permeate said layer of particles substantially immediately, and subjecting to pressure with or without heat.

"7. A method of causing adhesion, comprising substantially uniformly applying to a surface an adhesive-providing material in powder form. substantially uniformly applying to said powder a liquid atomized to a relatively fine degree, assembling and subjecting to bonding conditions.

8. A method of causing adhesion, comprising substantially uniformly applying to a surface an adhesive-providing material in powder form, substantially uniformly applying to said adhesive a liquid atomized to such a degree that the discrete units of said liquid are not substantially larger than the units of said powder, assembling and subjecting to bonding conditions.

9. A method of causing adhesion. comprising substantially uniformly applying to a surface an adhesive-providing material in powder form, substantially uniformly applying to said powder a liquid plasticizing medium atomized to such a degree that the discrete units of said liquid are not substantially larger than the units of said adhesive, assembling and subjecting to bonding conditions. a

10. A method of causing adhesion, comprising substantially uniformly applying to a surface an adhesive-providing material in powder form, substantially uniformly applying to said powder a liquid in the form of droplets not larger than six one-thousandths of an inch, assembling and subjecting to bonding conditions.

11. A method of causing adhesion, comprising substantially uniformly applying to a surface an adhesive-providing material in powder form, substantially uniformly applying to said adhesive a liquid atomized to a mist, assembling and subjecting to bonding conditions.

12. A method of causing adhesion, comprising substantially uniformly applying to a surface an adhesive-providing material in powder form, causing the several particles of said adhesive to be coated with a liquid to a substantially similar extent, said liquid contacting with said particles being in units of a fineness such that forces including surface tension tend to resist the passage of said liquid into said surface, assembling and subjecting to bonding conditions.

13. A method of causing adhesion, comprising substantially uniformly applying to a surface an adhesive-providing material in powder form, causing the several particles of said adhesive to be coated with a liquid to a substantially similar extent, said liquid contacting with said particles being in units of a fineness such that the chemical or physical forces set up tend to resist the passage of said liquid into said surface, assembling and subjecting to bonding conditions.

14. A'method of causing adhesion, comprising applying to a surface an atomized liquid, applying an adhesive-providing material, assembling and subjecting to bonding conditions.

15. A method of making plywood, comprising substantially uniformly applying an adhesive-providing material in powder form to the surface of a ply, substantially uniformly applying a liquid in an atomized condition, superposing another ply, and subjecting a completed assembly to bonding conditions.

16. A method of making plywood, comprising substantially uniformly applying liquid in an atomized condition to the surface of a ply, substantially uniformly applyingan adhesive-providing material in powder form, substantially uniformly applying a liquid in an atomized condition, superposing another ply, and subjecting a completed assembly to bonding conditions.

17. A method of making plywood, comprising substantially uniformly applying liquid in an atomized; condition to the surface of a ply, substantially uniformly applying an adhesiveproviding, material in powder form, superposing another ply, and subjecting a completed assembly to bonding conditions.

' THEODORE WILLIAMS DIKE." 

